Abstract:

Polymeric compositions for use in preparing a ballistic material and
ballistic materials capable of absorbing incoming projectiles prepared
from the polymeric material are disclosed The resulting ballistic
materials are also disclosed The materials have sufficient elasticity so
that the polymer or polymer blend does not shatter when stuck with a
high-velocity projectile The polymer blends ideally have one or more of
the following physical properties--a) a modulus of elasticity in the
range of around 12,500 psi and around 19,000-psi, b) a max stress psi in
the range of around 545 and around 985, and c) a tensile strength in the
range of around 3 50 ft-lbfln and around 11 OO ft-lbf/n The thickness of
the ballistic material is at least around 3 inches, with a size of around
4-5 inches square or diameter

Claims:

1. A ballistic material comprising a polymer or polymer blend which does
not shatter when stuck with a high-velocity projectile.

2. The ballistic material of claim 1, wherein the polymer or polymer
blends have one or more of the following physical properties:a) a modulus
of elasticity in the range of around 12,500 psi and around 19,000 psi,b)
a max stress psi in the range of around 545 and around 985, andc) a
tensile strength in the range of around 3.50 ft-lbf/in and around 11.00
ft-lbf/in.

3. The ballistic material of claim 1, wherein the material includes an
elastomeric polymer.

4. The ballistic material of claim 1, wherein the material is at least
about three inches in thickness, with a length and width, if square or
rectangular, a diameter, if round, of at least about four inches, or
comparable sizes if the material is in another shape.

5. The ballistic material of claim 1, wherein the material is at least
about twelve inches in thickness.

6. The ballistic material of claim 5, wherein center fire rounds up to .50
caliber do not penetrate more than about four or five inches into the
material.

7. The ballistic material of claim 1, wherein the polymers have a density
of 0.92 g/cm3, .+-.15%, a surface hardness of SD48, .+-.15%, a
tensile strength of 20 MPa, .+-.15%, a flexural modulus of 0.35 GPa,
.+-.15%, a linear expansion of 20.times.10-5/° C., .+-.15%,
elongation at break of 500%, .+-.15%, strain at yield of 20%, .+-.15%,
and a melting temperature range of around 120 to around 160.degree. C.

8. The ballistic material of claim 1, wherein the ballistic material is
formed by injection molding of thermoplastic polymers.

9. The ballistic material of claim 1, wherein the ballistic material is
formed by reaction injection molding (RIM) of thermoset polymers.

10. The ballistic material of claim 1, wherein the polymers comprise
between about 59% and about 90% linear low density polyethylene ("LLDPE")
by weight of the polymers, between about 5% and about 40% Hybar®
(5125) by weight of the polymers, and between about 0 and about 35 Engage
(8100), by weight of the polymers.

11. The ballistic material of claim 10, wherein the polymers comprise
preferably between about 5 and about 35% by weight of the polymers of
Engage (8100).

17. The ballistic material of claim 13, wherein the hardened material is
oriented within the material in a planar orientation.

18. The ballistic material of claim 13, wherein the hardened material is
oriented within the material in a plurality of planar orientations.

19. The ballistic material of claim 13, wherein the hardened material is
positioned at a certain depth within the material to enable the polymer
to reduce the velocity of the projectile, and with a certain depth of the
material behind the object to catch any fragments formed when the
projectile strikes one or more objects.

20. The ballistic material of any of claims 1-19, comprising interlocking
portions such that a plurality of blocks of the material can be connected
to each other.

21. The ballistic material of claim 20, wherein the interlocking portions
are male and female connectors.

22. A backstop for a firing range, comprising a plurality of the blocks of
claim 20.

23. Aircraft, spacecraft, ships, or ground vehicles, comprising a
plurality of the block of claim 20.

24. Training targets, comprising a plurality of the blocks of claim 120.

25. Protection for temporary or mobile military and/or police
installations, buildings, or bunkers, comprising a plurality of the
blocks of claim 20.

26. Pipelines comprising a plurality of the blocks of claim 20.

27. A polymeric composition as disclosed herein.

28. A method of making a polymeric composition as disclosed herein.

29. A projectile absorbing armor as disclosed herein.

30. A block for building a projectile absorbing armor as disclosed herein.

31. A method for making a projectile absorbing material as disclosed
herein.

32. Any other inventive features either individually or in combination
that are disclosed herein.

Description:

FIELD OF THE INVENTION

[0001]The invention is generally in the area of polymeric compositions for
use in preparing a ballistic material, and in ballistic materials capable
of absorbing incoming projectiles prepared from the polymeric material.

BACKGROUND OF THE INVENTION

[0002]There is often a need to absorb incoming high velocity projectiles,
such as bullets and the like. For example, armored vehicles and shooting
ranges need to stop such high-velocity projectiles.

[0003]Although there are several types of armor known for stopping these
projectiles, there are often limitations associated with these materials.
For example, ceramic body armor tends to crack after being struck with a
high-velocity projectile. It would therefore be advantageous to provide
additional materials for stopping these projectiles. The present
invention provides such materials, and articles of manufacture including
these materials.

SUMMARY OF THE INVENTION

[0004]The present invention generally relates to polymeric materials,
which can be thermoset or thermoplastic elastomeric materials, capable of
stopping one or more high speed projectiles, and articles of manufacture
which include these polymeric materials.

[0005]In a first embodiment, the materials are intended for use in
stopping pistol rounds and rim-fire rounds, such as 17 and 22 caliber
rounds. In a second embodiment, the materials are intended for use in
stopping these projectiles as well as higher velocity rounds, such as
rifle rounds, up to and including 50 cal. BMG rounds, as well as other
relatively high velocity projectiles.

[0006]In both embodiments, the materials can include a thermoplastic
polymer, such as a polyolefin, and enough of an elastomer to allow the
material to "re-heal" around a bullet, an elastomeric thermoset polymer,
which re-closes over the hole created by a bullet due to the elastomeric
properties, or blends thereof.

[0007]When the material is intended to stop pistol rounds and rim-fire
rounds, such as 17 and 22 caliber rounds, the polymers, or blends
thereof, have a density or a blended density of between about 0.795 and
about 0.995 grams/cm3. When the material is intended to stop high
velocity projectiles, such as rifle rounds, the density is between about
0.795 and about 1.25 grams/cm3. The desired density ranges can be
achieved using polymer foams and/or by adding suitable filler materials.

[0008]The materials have sufficient elasticity so that the polymer or
polymer blend does not shatter when stuck with a high-velocity
projectile. Ideally, the polymer(s) will "re-heal," or fuse back into a
solid form without cracking, after being penetrated by a first
projectile. The polymer blends ideally have one or more of the following
physical properties:

[0009]a) a modulus of elasticity in the range of around 12,500 psi and
around 19,000 psi,

[0010]b) a max stress psi in the range of around 545 and around 985, and

c) a tensile strength in the range of around 3.50 ft-lbf/in and around
11.00 ft-lbf/in.

[0011]It is generally been observed that when the material is intended to
be subjected to relatively higher velocity projectiles, it is desirable
to include a slightly higher amount of elastomeric polymer in the
material.

[0012]Ballistic apparatus made with the thermoplastic and/or thermoset
elastomeric polymeric materials were observed to prevent projectiles from
penetrating more than about four or five inches or so. When projectiles
penetrated further, the initial hole of entry closed very rapidly,
trapping the bullet in the apparatus.

[0013]Any low-density thermoplastic polymers, thermoset elastomers, or
blends thereof, which have the desired density and elasticity, or which
can be blended with a sufficient amount of elastomers to provide the
desired density and elasticity, to survive at least one or more impacts
with high-velocity projectiles, can be used.

[0014]Those of skill in the art can readily evaluate polymers and polymer
blends for their ability to stop incoming projectiles by preparing the
material and subjecting it to impact with the projectiles. As can be
appreciated, the thickness, length, and width will vary depending on a
number of factors, including the intended application (i.e., practice
targets or armor applications), and the selection of polymers.

[0015]The physical properties of polymers suitable for use in the present
invention, such as LLDPE, include a density of 0.92 g/cm3, ±15%,
a surface hardness of SD48, ±15%, a tensile strength of 20 MPa,
±15%, a flexural modulus of 0.35 GPa, ±15%, a linear expansion of
20×10-5/° C., ±15%, elongation at break of 500%, ±15%,
strain at yield of 20%, ±15%, and a melting temperature range of
around 120 to around 160° C.

[0016]The thermoplastic materials can be formed, for example, by injection
molding, and the thermoset materials can be formed, for example, by
reaction injection molding (RIM). In one embodiment, the monomers used in
the reaction injection molding process comprise Dow system spectrum RW
509 (Polyol)+Isonate MDI 5181.

[0017]In another embodiment, the polymers include between about 59% and
about 90% linear low density polyethylene ("LLDPE") by weight of the
polymers, between about 5% and about 40% Hybar® (5125) by weight of
the polymers, and between about 0 and about 35%, preferably between about
5 and about 35% Engage (8100), by weight of the polymers.

[0018]The bullet block configuration, designed to stop rimfire and pistol
rounds, is typically at least around 3 inches in thickness, and at least
around 4-5 inches square, or in diameter, if round, and equivalent sizes
if other shapes are employed. The maximum effective size is limited only
by the available space.

[0019]When the material is intended to stop high velocity projectiles,
such as rifle rounds, objects made of a hardened material, such as steel
and the like, are interspersed throughout the interior volume of the
material. The size of these objects ranges between about 1/4 and 1/2
inch, and the objects can be positioned in any suitable pattern that
provides an effective impediment to the path of the incoming projectile.
Depending on the intended use, the patterns can be used to stop incoming
fire from the front and/or back, the sides, and the top and/or bottom.
The simplest way to ensure that there is an object in the path of a
projectile is to place the objects in a plane throughout the material, in
each direction in which a projectile can enter the material. The objects
are positioned a certain depth within the material to enable the polymer
to reduce the velocity of the projectile, and with a certain depth of the
material behind the object to catch any fragments formed when the
projectile strikes one or more objects.

[0020]A plurality of blocks can be connected to each other by providing
the blocks with interlocking portions, such as male and female connectors
and the like. Ideally, where there are seams that might permit entry of a
high-velocity projectile, there is sufficient material from another
block, or from another portion of the same block, to provide adequate
protection. Structures comprising a plurality of these blocks, ideally
interlocked via the connecting means described above, are also within the
scope of the invention. Representative articles of manufacture include
backstops for firing range and home use, armor for vehicles and aircraft,
training targets, protection for temporary or mobile military and/or
police installations, buildings, bunkers, pipelines and/or any "critical
need" equipment which might require protection from ballistic impact, and
the like. The materials can be used as or in firearm backstops, e.g., at
a firing range or live-fire training facility, and as protective
ballistic armor disposed adjacent to a structure to be protected, such as
building structures, ground vehicles, aircraft, spacecraft, and ships.

[0021]Those skilled in the art will appreciate the above stated advantages
and other advantages and benefits of various additional embodiments
reading the following detailed description of the embodiments with
reference to the below-listed drawing figures.

[0022]According to common practice, the various features of the drawings
discussed below are not necessarily drawn to scale. Dimensions of various
features and elements in the drawings can be expanded or reduced to more
clearly illustrate the embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIGS. 1-3 are schematic illustrations of various interlocking blocks
made from materials described.

DETAILED DESCRIPTION

[0024]The present invention will be better understood with reference to
the following detailed description. Those skilled in the art will
appreciate the above stated advantages and other advantages and benefits
of various additional embodiments by reading the following detailed
description, particularly with reference to the above-referenced figures.

[0025]According to common practice, the various features of the drawings
discussed below are not necessarily drawn to scale. Dimensions of various
features and elements in the drawings can be expanded or reduced to more
clearly illustrate the embodiments of the invention.

I. Materials Intended for Stopping Pistol and Rim Fire Rounds

[0026]In one embodiment, the materials are intended for use in stopping
pistol rounds and rim-fire rounds, such as 17 and 22 caliber rounds.

II. Materials Intended for Stopping High Velocity Projectiles

[0027]In another second embodiment, the materials are intended for use in
stopping high velocity projectiles, such as rifle rounds, up to and
including 50 cal. BMG rounds, as well as other relatively high velocity
projectiles, in addition to the lower velocity pistol and rim-fire
rounds.

III. Polymeric Materials Useful for Preparing the Materials

[0028]In one aspect of both embodiments, the materials include a
thermoplastic polymer, such as a polyolefin, and enough of an elastomer
to allow the material to "re-heal" around a bullet. The blends of
thermoplastic polymers with elastomers are selected to provide
advantageous projectile-stopping properties.

[0029]In another aspect of both embodiments, the materials include an
elastomeric thermoset polymer, which re-closes over the hole created by a
bullet due to the elastomeric properties, even though it does not melt
and "re-heal" like the thermoplastic polymers. In a third aspect, the
materials include both a thermoplastic polymer and an elastomeric
thermoset polymer.

[0030]In the first embodiment, when the material is intended to stop
pistol rounds and rim-fire rounds, such as 17 and 22 caliber rounds, the
blends of the thermoplastic polymer and the elastomer have a blended
density of between about 0.795 and about 0.995 grams/cm3. In the
second embodiment, the blends of the thermoplastic polymer and the
elastomer have a blended density of between about 0.795 and about 1.25
grams/cm3. The desired density ranges can be achieved using polymer
foams, for example, by incorporating blowing agents into the polymeric
material as it is extruded to form articles of manufacture. Density can
also be controlled by adding suitable filler materials.

[0031]The blends of thermoplastic and elastomeric polymers, and/or the
elastomeric thermoset polymers, have sufficient elasticity so that the
polymer or polymer blend does not shatter when stuck with a high-velocity
projectile. Ideally, the polymer(s) will "re-heal," or fuse back into a
solid form without cracking, after being penetrated by a first
projectile.

[0032]The polymer blends ideally have one or more of the following
physical properties:

[0033]a) a modulus of elasticity in the range of around 12,500 psi and
around 19,000 psi,

[0034]b) a max stress psi in the range of around 545 and around 985, and

[0035]c) a tensile strength in the range of around 3.50 ft-lbf/in and
around 11.00 ft-lbf/in.

[0036]It is generally been observed that when the material is intended to
be subjected to relatively higher velocity projectiles, it is desirable
to include a slightly higher amount of elastomeric polymer in the
material.

[0037]Examples of suitable thermoplastic and thermoset materials are
described in more detail below.

[0038]A. Thermoplastic Materials

[0039]There are a number of suitable low-density thermoplastic polymers
that have the desired density and elasticity, or which can be blended
with a sufficient amount of elastomers to provide the desired density and
elasticity, to survive at least one or more impacts with high-velocity
projectiles. There are likewise a number of suitable thermoset
elastomeric polymers that have the desired density and elasticity, or
which can be blended with a sufficient amount of elastomers to provide
the desired density and elasticity, to survive at least one or more
impacts with high-velocity projectiles.

[0040]Representative thermoplastic polymers include linear low density
polyethylene (LLDPE). Representative thermoplastic polymers include, but
are not limited to, LL 6100 and LL 6200 (Exxon Mobil), Dowlex® LLDPE
1002.09 and 1002.28, Montell® 16502F3 Butene LLDPE, Novacor® PI
2024a, 2035, 2037, and 2045A LLDPE, elastomers such as Dow NG3310 (a
linear low density polyethylene copolymer containing 93% by weight
ethylene and 7% by weight octene), 1300, 8250, 1280, Dow Affinity®
EG8150G and EG8200 polyolefin plastomers, 58200.03 and other
polyethylenes disclosed in U.S. Pat. No. 6,270,891, the contents of which
are hereby incorporated by reference, damping agents such as Hybrar®
elastomers such as Hybrar® 4033, 4055, 5125, 8004, 2004, 8007, 7125,
and 8006, and Engage® 8100 or Engage® 8200. Hybrar® are a series
of high performance thermoplastic rubbers developed by Kuraray Co., LTD.
These thermoplastic rubbers have high vibration damping properties at
room temperature, and are commercially available in both hydrogenated and
non-hydrogenated grades. In addition to superior vibration damping
properties, the hydrogenated grades also exhibit excellent miscibility
with polypropylene, and may be used to produce blends with excellent
flexibility and mechanical properties. Hybrar® is available in a
triblock type having polystyrene blocks and a vinyl bonded rich
polyisoprene block. Engage is a polyolefin plastomer, comprising a
co-polymer of ethylene and octane. Engage 8100 (also known as EG8100G)
has a specific gravity of between 0.85 and 0.91.

[0041]The physical properties of LLDPE include a density of 0.92
g/cm3, a surface hardness of SD48, a tensile strength of 20 MPa, a
flexural modulus of 0.35 GPa, linear expansion of 20×10-5/°
C., elongation at break of 500%, strain at yield of 20%, and a melting
temperature range of 120 to 160° C. Polymers which have properties
within about 15% of these ranges, in either direction, are suitable for
use in the materials described herein.

[0042]When the materials, and articles that include the materials, are
intended to stop pistol rounds or rimfire rifle rounds, such as 17
caliber or 22 caliber rifle rounds, the following has been observed. A
material prepared from 100% LLDPE will stop a few bullets, from 38
special to 9 mm, but will not re-heal, and tends to crack upon impact.
However, by incorporating about 20% by weight of a damping agent and
about 10% by weight of an elastomer, the material is capable of stopping
and containing a relatively high number of rounds such as 38 special, 22
long rifle, 22 short rifle, 40 cal., 45 cal., 9 mm, 357 magnum, and 22
magnum rifle rounds. In one embodiment, a "bullet block" prepared from
the material stopped a minimum of 5,000 rounds.

[0043]Accordingly, in one embodiment, the polymers include between about
59% and about 90% linear low density polyethylene ("LLDPE") by weight of
the polymers, between about 5% and about 40% of a damping
agent/elastomer, by weight of the polymers. Within this embodiment, the
following compositions have been successfully evaluated: a) 59% by weight
of LLDPE and 40% by weight damping agent; b) 59% by weight of LLDPE, 5%
by weight of damping agent, and 35% by weight elastomer; c) 94% by weight
of LLDPE and 5% by weight damping agent; d) 94% by weight LLDPE and 5%
elastomer; 69% by weight of LLDPE, 20% damping agent, and 10% by weight
elastomer.

[0044]When the materials, and articles that include the materials, are
intended to stop higher velocity projectiles, such as rifle rounds, the
following has been observed. As with the first embodiment, material
prepared from 100% LLDPE will stop a few bullets, but will not re-heal,
and cracks upon impact. However, incorporation of at least about 20% by
weight of a damping agent or an elastomer will enable the material to
stop and contain a relatively high number of rounds such as 38 special,
22 long rifle, 22 short rifle, 40 cal., 45 cal., 9 mm, 357 magnum, and 22
magnum rifle rounds.

[0045]In one embodiment of the material used to stop high velocity
projectiles, the polymers include between about 59% and about 90% linear
low density polyethylene ("LLDPE") by weight of the polymers, between
about 5% and about 40% preferably between about 5 and about 35%, of an
elastomer/damping agent, by weight of the polymers. In another
embodiment, the materials include about 79% LLDPE by weight of the
polymers, and about damping agent by weight of the polymers.

[0046]The materials can typically be formed by injection molding, which
typically involves obtaining solid particles (such as chips) of the
thermoplastic polymer(s), melting them, and placing the molten
thermoplastic materials in a suitable mold. After cooling, the resulting
material is removed from the mold.

[0047]The manner in which the thermoplastic material inhibits penetration
of high-velocity projectiles can be described generally as follows. As a
high-velocity projectile enters the material, its kinetic energy is
converted into heat; and the thermoplastic polymers in the region in
front of the projectile are compressed and melted. The molten polymer
then flows past the projectile into the region behind the projectile,
where it cools and hardens. The result is that the track of the
projectile is of smaller diameter than the projectile itself. Further,
because the molten region ahead of the projectile generally extends
beyond the diameter of the projectile itself, the shear stress imposed by
the surface of this molten polymer volume moving through the solid
provides an additional sink for the kinetic energy of the projectile.

[0048]Also, when the polymer is pulled or stretched in this super heated
state, it cools quickly, and reverts to its congealed state. As it cools,
the thermoplastic polymeric material attempts to return to its original
position. As a result, the cooling polymer acts like an extremely
aggressive adhesive with respect to anything it contacts, such as a
spinning projectile. This adhesion can be promoted by using a compatible
adhesion promoting agent, such as polyethylene acrylic acid.

[0049]Ballistic apparatus made with the thermoplastic polymeric material
were observed to prevent projectiles from penetrating more than about
four or five inches. When projectiles penetrated further, the initial
hole of entry closed very rapidly, trapping the bullet in the apparatus.
Because of the energy absorbing properties of the thermoplastic polymeric
material, and the expansion of the polymeric material as it cools, the
projectile is truly captured by the apparatus with no chance of escape,
and stops within a short distance.

[0050]For projectiles that are spinning (e.g., projectiles fired from a
rifled barrel or rifled slugs fired from a smooth bore barrel, such as a
shotgun), it is believed that the energy resulting in the rotational
motion of the projectile is at least partially dissipated by the shear
between any projectile surface in contact with polymer, and by the
pumping action that the projectile rotation exerts on the molten polymer.
Rotation of the projectile effectively pumps molten polymer to the rear
of the projectile, dissipating the projectile energy, and helping to slow
its forward motion (in much the same way that a twist drill ceases to
penetrate a wood block when it stops rotating).

[0051]Those of skill in the art can readily evaluate polymers and polymer
blends for their ability to stop high-velocity projectiles, for example,
by preparing the material in a form that has a desired thickness, length,
and width for the intended application, and subjecting it to impact with
high-velocity projectiles. As can be appreciated, the thickness, length,
and width will vary depending on a number of factors, including the
intended application (i.e., practice targets or armor applications), and
the selection of polymers.

[0052]B. Thermoset Materials

[0053]Any thermoset polymer(s) can be used that provides adequate
elasticity such that the material can stop incoming projectiles.
Representative thermoset elastomeric polymers include elastomeric
polyurethanes, such as those described, for example, in U.S. Pat. No.
6,271,305 to Rajalingam et al., EPDM (an elastomeric compound that is
manufactured from ethylene, propylene, and a small amount of diene
monomer), and the thermoset elastomeric materials described in U.S. Pat.
No. 5,869,591, the contents of which are hereby incorporated by
reference. Also suitable are thermoset systems like Bayflex 110-50,
110-35, and 110-80, and MP10000 (Bayer Corporation). In one embodiment,
the monomers used in the reaction injection molding process comprise Dow
system spectrum RW 509 (Polyol)+Isonate MDI 5181.

[0054]The thermoset materials are typically prepared by reaction injection
molding (RIM). For example, polyurethane reaction injection molding (RIM)
can be used to prepare thermoset polyurethane RIM elastomeric parts,
which tend to have relatively high strength and relatively low weight.
Like thermoplastic injection molding, RIM uses molds to form parts.

[0055]RIM is capable of providing thermoset resins with a broad range of
properties. The reaction involves the reaction of two liquid components,
unlike the conventional pellet form of most thermoplastics used in
injection molding. These liquid components--an isocyanate and a
polyol--are often referred to as polyurethane RIM systems.

[0056]Depending on how the polyurethane RIM system is formulated, the
resulting molded parts can be a foam or a solid, and can be made
relatively flexible (i.e., elastomeric).

[0057]In RIM processing, the two liquid components are held in separate,
temperature-controlled feed tanks equipped with agitators, and then fed
through supply lines to metering units which meter both components, at
high pressure, to a mixhead device. The components are then subjected to
high velocity impingement in a mix chamber, and the mixed liquids then
flow into the mold at approximately atmospheric pressure. Inside the
mold, the liquid undergoes an exothermic chemical reaction, which forms
the polyurethane polymer.

[0058]The manner in which the thermoset elastomeric material inhibits
penetration of high-velocity projectiles can be described generally as
follows. As a high-velocity projectile enters the material, it punches a
hole in the thermoset elastomeric material. Unlike the thermoplastic
material, which melts and then flows around the projectile, the thermoset
elastomeric material does not crack, but rather, spreads open to form a
hole into which the projectile enters. Due to the thermoplastic nature of
the thermoset polymer, after the bullet passes through the hole, the
elastomeric nature of the material allows it to re-close the hole around
the space created by the projectile. Thus, unlike the thermoplastic
material, which re-forms around the projectile, the thermoplastic
material re-closes around the projectile, leaving behind a seam where the
projectile originally entered the material.

[0059]Ballistic apparatus made with the thermoset polymeric material were
also observed to prevent projectiles from penetrating more than about
four or five inches or so. When projectiles penetrated further, the
initial hole of entry re-closed very rapidly, trapping the bullet in the
apparatus. The energy absorbing properties of the thermoplastic polymeric
material capture the projectile, with no chance of escape, within a
relatively short distance.

[0060]For projectiles that are spinning (e.g., projectiles fired from a
rifled barrel or rifled slugs fired from a smooth bore barrel, such as a
shotgun), as with the thermoplastic material, it is believed that the
energy resulting in the rotational motion of the projectile is at least
partially dissipated by the shear between any projectile surface in
contact with the thermoset polymer.

[0061]C. Optional Additional Components

[0062]Rubbers (such as Vistalon®, natural rubber, CPE (chlorinated
polyethylene), TPO (thermoplastic polyolefins), TPV (thermoplastic
polyolefin vulcanite), or EPDM rubbers) can optionally be added to
provide desirable energy absorption properties at low temperature uses
(e.g., in arctic or Antarctic environments). Fibers and ceramic fillers
can optionally be added to help provide density changes and initiate
tumbling in high temperature uses (e.g., in desert or tropical
environments). Inclusion of both types of additives can provide a
material suitable for use in a wide range of environments.

[0063]The polymeric material can contain a number of other components to
provide desirable properties, including orienting the polymer chains
during extrusion, entangling the polymer chains, and providing density
gradients within the polymeric material to induce early tumbling or
aspect ratio change. Typical compositions include (percentages are by
weight based on the total weight of polymeric material):

[0064]Acrylic acid (for adhesion control, in amounts ranging from about
0.25 to about 10%;

[0065]Macro and micro fibers, such as silica, alumina, or organic fibers,
in amounts ranging from 0 to about 50%, more particularly from about 5 to
about 10%;

[0066]Peroxide-containing or silane-containing curing agents, in amounts
ranging from 0 to about 4%; the material can contain at least two
different types of silanes simultaneously, which may each perform
independent functions: (1) a curing silane, typically a vinyl silane used
with peroxide and catalyst; and (2) a treatment silane, typically of the
amino or epoxy types for pigment treatment, to control coupling and melt
rheology.

[0067]Colorants, in amounts ranging from 0 to about 12%; Plastomer (for
control of crystallinity and curing) in amounts ranging from 0 to about
20% (e.g., ENGAGE® 8540 (Dupont Dow); EXXACT® 2030 (Exxon),
etc.);

[0068]Vistalon rubber (for control of crystallinity and to provide
entanglement at low temperatures) in amounts ranging from 0 to about 30%;

[0069]Natural rubber (desirably in crumb form, to provide elasticity and
as a filler) in amounts ranging from 0 to about 25%;

[0070]EPDM rubber (desirably in crumb form, to provide low temperature
entanglement) in amounts ranging from 0 to about 50%;

[0071]Grafting/crosslinking catalyst(s) (such as catalyst T-12, Air
Products, Inc.) in amounts ranging from 0 to about 0.5%;

[0072]Lubricants (such as a wax or metal stearate, such as zinc stearate)
in amounts ranging from 0 to about 12%;

[0073]Wetting agents (such as stearic acid) in amounts ranging from 0 to
about 4%;

[0075]Vulcanizing agents (such as sulfur-containing crosslinking
compounds) in amounts ranging from 0 to about 8%. It is understood that,
when vulcanizing agents are used, zinc oxide and zinc containing
derivatives can be included to accelerate the reaction, and magnesium
oxide (such as Mag-lite "D" from Merck) can be used to modify and
stabilize the vulcanization mechanisms. Additional components can include
fire retardants, such as magnesium hydroxide, boric acid, zinc borate,
aluminum trihydrate, and various clays including but not limited to
montmorillonite, talc, bentonite, and kaolin (nano-clays).

IV. Incorporation of Objects Into the Materials

[0076]In one aspect of this embodiment, objects made of a hardened
material, such as steel and the like, are interspersed throughout the
interior volume of the material. The size of these objects ranges between
about 1/4 and 1/2 inch. The objects can be placed in the material in
various arrangements to retard the penetration of the projectiles through
the material.

[0077]In one embodiment, the hardened objects comprise ceramic materials.
As used herein, the term "ceramic" can include, but is not limited to,
materials made from zirconia, alumina, borates, and/or silica. The
ceramics may be sintered (e.g., fired in a kiln to develop their grain
size) or unsintered. They may be shaped into desired forms, e.g.,
spheres, plates and/or very fine to coarse beads. Examples of silicas
include glass, noveculite, quartz, sand, each having various particle
sizes, and combinations of these. Ceramics made from cements of silica,
Portland cement, alumina cements, magnesium oxide cements, phosphorate
cements, and/or hydrocements are especially good and very economical.
They have compression values of 15,000 to 60,000 psi without sintering in
a kiln. These ceramic cements can combined with the polymeric material of
the invention and can then be shaped from a liquid and poured into a
void, which forms a mold for the apparatus of the invention. They may be
pre-formed into plates, spheres or any other desired shape with the
resulting material having the approximate hardness of sintered ceramic.
Polymer ceramic cement versions used are so flexible they can stop
projectiles without shattering completely.

[0078]It is believed that such hardened objects increase the ability of
the armor assembled from the blocks to absorb incoming projectiles in at
least two ways. First, the directional path of an incoming projectile
that encounters one of the hardened objects is deflected in such a manner
as to increase the rate at which the projectile decelerates as it
penetrates into the armor. Second, incoming projectiles may become
deformed, disintegrate, or shatter upon encountering one or more of the
hardened objects and such deformation, disintegration, or shattering will
also tend to impede penetration into the armor. When these objects are
present in the material, and the material includes an appropriate blend
of thermoplastic and elastomeric polymers, the material can even stop
high velocity rounds such as 50 cal. BMG.

[0079]FIGS. 1-3 are schematic illustrations of exemplary patterns in which
the objects are oriented in the materials to provide an impediment to the
path of oncoming projectiles. Each of the Figures are a schematic
representation of a horizontal cross-section of a block B made from
material of the present invention and having the objects O interspersed
within the interior of the block. In FIG. 1, the objects O are arranged
as illustrated in U.S. patent application Ser. No. 11/180,843, which is
incorporated by reference herein for all purposes. The objects O are
arranged in a plurality of two-dimensional matrix structures S that
extend radially outward from a central location C within the interior of
the block B forming a "star" configuration similar to spokes of a wheel
extending radially outward from the central location. Each matrix
structure S includes a single, radial row of hardened objects O arranged
in multiple vertical columns, each vertical column extending from a
bottom surface of the block B to a top surface of the block.

[0080]FIG. 2, illustrates an alternative arrangement of the objects O that
includes the matrix structures or spokes S oriented in the "star"
configuration. In FIG. 2, the block B includes arcuate walls W of
hardened objects O between respective spokes S. Each arcuate wall W
includes a plurality of vertical columns of hardened objects O so that
the walls form a generally circular barrier surrounding the central
location C extending the height of the block.

[0081]FIG. 3, illustrates an alternative arrangement of the objects O that
includes three parallel two-dimensional matrix structures S of hardened
objects O. In FIG. 3, one of the structures S passes through the middle
of the block B, and the other two structures are spaced apart from and
generally parallel to the middle structure. As with the previous
embodiments, the matrix structures S of FIG. 3 include a plurality of
vertical columns of objects O that extend from the bottom of the block to
the top of the block to impede the penetration of a projective that
enters at any vertical location or angle into the block.

[0082]Reference is made to the co-assigned U.S. patent application Ser.
No. 11/620,180, filed Jan. 8, 2007 having attorney docket number B219
1021.1, which is incorporated by reference herein for all purposes, for
additional information and orientations of the hardened objects O in the
block B. Further, it is contemplated that the hardened objects could be
otherwise, arranged or could be omitted from the material for impeding
penetration of the projectile without departing from the invention. Other
patterns can be used, but in any embodiment, the patterns ideally
position a solid object in any possible path in which a high velocity
projectile can enter the material. The objects in the patterns are
ideally spaced at least about 1-3 inches, typically about 4-5 inches,
inside the material, so that the incoming projectile has contact with at
least some of the polymeric material before coming into contact with the
object. Also, the objects are ideally spaced such that any fragments
resulting from the projectile hitting the objects have sufficient
polymeric material behind them to catch such fragments.

[0083]In the two dimensional and/or three dimensional blocks, the objects
are present in a concentration of between about 2500 ball bearings in the
star pattern, and between about 5 and about 40 percent of the total
volume of the polymeric material, typically between about 8 and 20
percent of the volume. When used in patterns that only stop objects in
one or two dimensions, the volume can be as low as 3 percent of the total
volume of polymeric material, but are typically present in about 5 to
about 10 percent of the total volume.

V. Configuration of the Materials

[0084]The bullet block configuration, designed to stop rimfire and pistol
rounds, is typically at least around 3 inches in thickness, and at least
around 4-5 inches square, or in diameter, if round, and equivalent sizes
if other shapes are employed. The maximum effective size is limited only
by the available space.

[0085]When the material is intended to stop high velocity projectiles, the
thickness of the material is at least around 4-5 inches, and the height
and width are ideally at least about 8-9 inches, more typically at least
around 12 inches, but the upper limit of the size is limited only by the
available space. As discussed in more detail below, the material can be
formed into interlocking shapes, and thus form a protective shield of
virtually any size and shape.

[0086]The materials that optionally include the hardened materials can be
formed into relatively lightweight polymeric blocks that are readily
assembled into a projectile absorbing armor or into readily-assembled
building block shapes. One embodiment of the block shapes is shown in
FIG. 4, in which the blocks can interlock in three dimensions.

[0087]In one embodiment, the material is formed into "building blocks" so
that one can construct a projectile absorbing armor that includes a
plurality of the blocks. This can be accomplished using means known in
the art.

[0088]One means for connecting a plurality of blocks is to provide the
blocks with interlocking portions, such as male and female connectors.
Male and female connectors allow the blocks to be connected in a
horizontal fashion. As with conventional log home construction, the
polymeric materials can include a projection on a top or bottom surface,
and a recess on the bottom or top surface, respectively. The projection
and recess enable the blocks to be stacked in a vertical fashion.
However, other means of connecting a plurality of blocks can be
envisioned, and any arrangement that allows the blocks to be assembled in
a desired shape, to provide a desired level of protection, can be used.
Ideally, where there are seams that might permit entry of a high-velocity
projectile, there is sufficient material from another block, or from
another portion of the same block, to provide adequate protection.

[0089]As the angle of incidence to the surface plane of the block
increases, the ability of the polymeric material to capture and absorb
projectiles varies in accordance with the velocity of the projectile and
the density of the polymer. Relatively low velocity projectiles
encountering the surface plane of the armor of the block at a relatively
high level of incidence tend to bounce or ricochet off the material if
the surface density is too high, for example, around 0.95 to 1.5 g/cc or
higher. Thus, it is advantageous in some cases to fabricate the block in
multiple layers with an outward facing layer of a relatively low density
material, at the surface of the block, and a second, interior layer of a
relatively higher density material below the first layer, with both
density ranges within the ranges stated above. In one embodiment, the
layers are formed from the same polymer(s), but the relatively lower
density layer is more highly foamed. Alternatively, two different
polymeric formations may be joined together, with a lower density polymer
disposed toward the direction of incoming projectiles.

VI. Three Dimensional Objects Prepared From the Materials

[0090]Structures comprising a plurality of these blocks, ideally
interlocked via the connecting means described above, are also within the
scope of the invention. In one embodiment, the structures comprise a body
formed at least partially of a polymeric material described herein,
ideally with a plurality of hardened objects are within the material. The
plurality of hardened objects can be arranged into a predetermined matrix
selected to ensure that a projectile moving through the body is likely to
encounter at least one of the hardened objects.

[0091]Representative articles of manufacture include backstops for firing
range and home use, armor for vehicles and aircraft, training targets,
protection for temporary or mobile military and/or police installations,
buildings, bunkers, pipelines and/or any "critical need" equipment which
might require protection from ballistic impact, and the like. The
materials can be used as or in firearm backstops, e.g., at a firing range
or live-fire training facility, and as protective ballistic armor
disposed adjacent to a structure to be protected, such as building
structures, ground vehicles, aircraft, spacecraft, and ships.

[0092]The present invention will be better understood with reference to
the following non-limiting example.

Example 1

Composition for Reaction Injection Molding of a Ballistic Material

[0093]The following composition was prepared for use in stopping hand gun
and rifle rounds. The polymeric material is a polyurethane, and the
material is formed by reaction injection molding.

[0094]The polyurethane is prepared from a polyol and a polyisocyanate. In
this example, the polyol is Dow® system Spectrum RW 509 (Polyol) and
Isonate® 5181 methylene diphenyl isocyanate (MDI). The ratio of
isocyanate to polyol was typically about 0.420/1.

[0095]The following procedure was used to mold blocks of the ballistic
material.

[0096]A reaction injection molding process was used, with a mold
temperature ranging from 140° F. on the core and 150° F. on
the cavity. The degree of nucleation was typically between about 1.0 and
about 0.90 degrees API when the ballistic material was designed to stop
rifle bullets, and between about 0.75 and 0.85 degrees API when the
ballistic material was designed to stop handgun bullets. The tank
pressure was 60 psi when the material was designed to stop handgun
bullets, and 0 psi when the material was designed to stop rifle bullets.
The re-circulation pressure for all processes was set at 80 psi.

[0097]The shot size (or "batch size") for the material designed to stop
handgun bullets was between around 40 to 48 lb shot, and for the material
designed to stop rifle bullets, the shot size was 49 to 55 lb. The
specific gravity of the polyol (RW509 POLYOL) was around 1.02, and the
specific gravity for the isocyanate (MDI 5181 ISO) was around 1.22. In
some embodiments of the material intended for use in stopping rifle
bullets, ball bearings were added at an amount of between about 10 to
about 12 pounds of ball bearings to about 49 to about 55 pounds of
polymer.

[0098]Temperatures of the isocyate were generally kept at between about
95° F. to about 105° F., and temperatures of the polyol
were generally kept at between about 95° F. and about 105°
F.

[0099]The parts were molded with a 4 minute cure time, and each part was
weighed to verify its density.

[0100]After the first part was molded and inspected, a plaque (3.5'' by
5.5'' by 1/4'') of the material was prepared, and taken to a laboratory
for evaluation of the physical properties using an Instron. Three dies
were used, and tear strength, flexural modulus, and elongation at break
were measured.

[0101]For materials prepared using the above-described RIM process, the
physical properties were typically as follows:

[0102]a) the specific gravity ranged from between about 0.93 to about
1.12;

[0103]b) the flexural modulus ranged from a minimum of 43,500 psi for
materials intended for use in stopping handgun bullets, and a minimum of
65,250 psi for materials intended to stop rifle bullets;

[0104]c) the elongation at break for materials intended for use in
stopping handgun bullets was a minimum of 75%, and for materials intended
for use in stopping rifle bullets, the minimum was 50%;

[0105]d) the minimum tear strength for materials intended for use in
stopping handgun bullets 364 psi, and the minimum tear strength for
materials intended for use in stopping rifle bullets was 510 psi.

[0106]The material can be prepared in just about any color, including the
natural color of the resulting polymer, though black and red pigments
have been added.

[0107]The foregoing description illustrates and describes various
embodiments of the present invention. As various changes could be made in
the above construction without departing from the scope of the invention,
it is intended that all matter contained in the above description or
shown in the accompanying drawings shall be interpreted as illustrative
and not in a limiting sense. Furthermore, the scope of the invention
covers various modifications, combinations, additions, and alterations,
etc., of the above-described embodiments that are within the scope of the
claims. Additionally, the disclosure shows and describes only selected
embodiments of the invention, but the invention is capable of use in
various other combinations, modifications, and environments and is
capable of changes or modifications within the scope of the inventive
concept as expressed herein, commensurate with the above teachings,
and/or within the skill or knowledge of the relevant art. Furthermore,
certain features and characteristics of each embodiment may be
selectively interchanged and applied to other illustrated and
non-illustrated embodiments of the invention without departing from the
scope of the invention.